With damp hands, divide the mixture into approximately 150g/5oz portions and shape into patties.

Heat the remaining olive oil in a frying pan and fry the patties for 3-4 minutes on both sides, or until golden-brown. Heat a griddle pan until smoking, then add the patties and fry for a further 1-2 minutes on both sides, or until there are deep char lines on both sides.

To serve, place the patties into burger buns and arrange over the toppings of your choice.